title: Assessing lower-body peak power in elite rugby-union players.
abstract: Resistance training at the load that maximizes peak power (Pmax) may produce greater increases in peak power than other loads. Pmax for lower-body lifts can occur with no loading but whether Pmax can be increased further with negative loading is unclear. The purpose of this investigation was therefore to determine lower-body Pmax (jump squat) using a spectrum of loads. Box squat 1 repetition maximum (1RM) was measured in 18 elite rugby-union players. Pmax was then determined using loads of -28 to 60%1RM. Elastic bands were used to unload body weight for negative loads. Jump squat Pmax occurred with no loading (body weight: 8,880 ± 2,186 W) in all but 2 subjects. There was a discontinuity in the power-load relationship for the jump squat, possibly because of the increased countermovement in the body weight jump. The self-selected depth (dip) before the propulsive phase of the jump was greater by 24 ± 11 to 40 ± 16% (moderate to large effect size) than all positive loads. These findings highlight methodological issues that need to be taken into consideration when comparing power outputs of loaded and unloaded jumps.
authors.affiliation: Division of Sport and Recreation, Institute of Sport and Recreation Research New Zealand, AUT University, Auckland, New Zealand. argy15@hotmail.com
authors.forename: Christos K
authors.initials: CK
authors.lastname: Argus
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Gill
authors.forename: Justin W L
authors.initials: JW
authors.lastname: Keogh
authors.forename: Will G
authors.initials: WG
authors.lastname: Hopkins
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D005538:Football / Q000502:physiology*; D006801:Humans; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D055070:Resistance Training; D055815:Young Adult